The Hearst Tower 959 Eighth Avenue New York, NY Jessica Lucas Mechanical Option.

The Hearst Tower959 Eighth Avenue

New York, NY

Jessica LucasMechanical Option

The Hearst TowerNew York, NY

Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Presentation Outline


Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Site and Location


Located along 8th Avenue between 56th & 57th Street in Midtown Manhattan

Constructed through the center of the original Hearst Headquarters (1928)

Landmark building will be hollowed with new Tower constructed through center


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Project Team

Building Owner: Hearst Corporation

Architect: Foster and Partners

Associate Architect: Adamson Associates

MEP: Flack+Kurtz

CM: Turner Construction



Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Size and Architecture


• 42 stories• 856,000 SF• 2000 Hearst Employees

Most notable features:• Diagrid Facade• LEED Gold certification

Architectural Program• Open Office• Auditorium• Test Kitchens• Television Studio


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Existing Mechanical System


Central Chilled Water Plant serving a low temperature Variable Air Volume system

Waterside System

• 4-1000 ton cooling towers on roof level

• 2-1200 ton & 1-400 ton electric chillers in basement chiller plant

Airside System

• 4-110,000 CFM AHU’s, serve office tower

• Indoor Design Conditions

• 75F for cooling/50% RH cooling

• 70F for heating

• Air supplied to spaces at 45F


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Proposed Mechanical System:

Combining Steam Driven Absorption Cooling with a Dedicated Outdoor Air/ Radiant Floor System


Replace electric chillers with double effect steam driven absorptionReplace the central VAV AHU’s with dedicated outdoor air (DOAS) unitsInstall radiant floors to parallel DOAS for both heating & cooling


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Goals of Proposed System

• Ensure ASHRAE Std. 62.1-2004 compliance

• Obtain the LEED point for IAQ

• Lessen the Tower’s dependence on an overextended electric grid

• Lower annual operating cost

• Meet the original criteria to create a reliable Class “A” office building



Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Proposed Mechanical System:Dedicated Outdoor Air System

(DOAS)


What is DOAS?

• 100% OA unit based on ASHRAE Std.62.1

• Decouples Sensible & Latent Loads

• Utilizes Energy Recovery

DOAS for Hearst:

• Std. 62.1 +30% OA for IAQ LEED point

• Utilize an Enthalpy Wheel for total energy recovery

• Maintain 45F supply air temperature


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Proposed Mechanical System:


The resulting DOAS Design:

• 3-40,000 CFM Semco units with a molecular sieve desiccant coated enthalpy wheel

• Chiller plant downsized by 30%

• Cooling coil load decreased from 44 tons to 10.5 tons

• Supply Air at 45F and saturation


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Proposed Mechanical System:Radiant Floor Heating and Cooling


Optimize layout based on daylighting study using AGI32 software


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Proposed Mechanical System:Absorption Chillers


3-600 ton Double-effect chillers arranged in parallel

Lithium Bromide/Water- no CFC’s or HCFC’s

New chiller plant requires 60 kW of electric input, compared to 1,941 kW used in the electric chiller plant

Con Edison offers incentives for steam driven cooling during the cooling season


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Proposed Mechanical System:Additional Alternative


Can I save even more with an Electric Chiller Plant w/DOAS System?

• Still 30% reduction in chiller plant size

• Still only minimum CFM

• Higher COP with vapor compression cycle


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Proposed Mechanical System:Cost Analysis


Electric w/VAV

Electric w/DOAS

Absorption w/DOAS

Total Electricity

$93.1 M $41.2 M $33.9 M

Total Steam

$31 M $29.4 M $39.4 M

Total O&M

$25.6 M $14.5 M $15.9 M

20 year LCC

$156.4 M $93.4 M $98.8 M


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Proposed Mechanical System:Mechanical Summary


Electric/DOAS

• Lowest LCC

• Lowest Operating Cost

• Higher COP

However…

• Still dependent on electric grid

• Black-outs = diminished reliability

Recommendation: Absorption/DOAS Radiant


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Electrical System Breadth


Current Electrical System:

• 4-4000 amp service take-offs

• Each takeoff is served by 1-6000 amp service switch

• Each takeoff provides 480/277 V 3 phase service from primary

transformers

Daylighting & Occupancy sensors used throughout for energy conservation

High efficiency ballasts, helped obtain rebates from NYSERDA


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions



Existing Chiller Plant

Chiller 1&2: 2000 A fuses, 6 sets of 3- 400 MCM with 1-#3/0 ground in 3”conduit

Chiller 3: 800 A fuse, 2 sets of 3-500 MCM with 1-#2/0 ground in 3.5” conduit

Cost of wiring & conduit: $932.00/LF

New Plant

Chiller 1,2,3: 40 A fuses, 1 set of 3-#6 with 1-#10 ground in 1”conduit

Cost of wiring & conduit: $46.80/LF


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions



Existing VAV System

8 supply fans- 124 FLA

4 return fans- 65 FLA

MCC total connected load of 1,697 FLA

Proposed DOAS System

3 supply fans- 77 FLA

3 return fans- 65 FLA

MCC total connected load of 632 FLA


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Electrical System Breadth:Conclusions


Downsizing equipment results in:

First cost savings for wire & conduits

Decreased switch sizes

Increased distribution board space

Allows for easier installation


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Structural System Breadth:Current System

Half of the foundation is supported by spread footings, half by caissons

Primary latera l support provided by the perimeter Diagrid

Secondary lateral system defined by bracedframe at the service core

Structure below 10 th floor uses a mega-column systemto support a large unbraced height



Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Structural System Breadth:Effect of Radiant Floors


• International Fire Code 2003 2 hour fire rating

• Vulcraft Deck 6” slab

• Radiant tubes 1.5” concrete cover

• Check deck, beams, girders with additional concrete load

• LRFD Manual example for Composite W-shape flexural

member design (unshored construction)


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Structural System Breadth:Conclusion

Allowable Shear Stud Capacity greater than Maximum shear under applied loading

Vu < ΣQn i.e. 42.8 k < 451 k

Allowable Flexural Capacity exceedsMaximum moment under the appliedfactored loading

Mu < ФMn i.e. 428 ft-k < 450 ft-k

No changes needed to member sizes!



Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Conclusions


Proposed mechanical system satisfied criteria set forth at the beginning of the design process:

Lower annual operating costs

Obtain LEED point for IAQ

Lessen dependence on electric grid

Increase reliability

Maintain Class “A” market status

Positively impact electrical system by lowering first cost & allowing for easier installation

No nominal impact on Structural system


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Acknowledgements


A huge Thank You to:

JJ, Dr. Freihaut, Dr. Bahnfleth, Dr. Mumma, Dr. Srebric and the rest of the AE Faculty.

My fellow classmates especially Jenny, Jayme, Yulien, Dave, Bryan, and Adam.

Paul Reitz of Flack+Kurtz


Introduction

Background

Current System

Proposed System

Cost Analysis

Electrical Breadth

Structural Breadth

Conclusions

Questions??


The Hearst Tower 959 Eighth Avenue New York, NY Jessica Lucas Mechanical Option.

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